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April 1987

Tactile Discrimination Learning Deficits in Alzheimer's and Parkinson's Diseases

Author Affiliations

From the Department of Medicine (Division of Neurology), University of Toronto, Mount Sinai Hospital, and Baycrest Centre for Geriatric Care, Toronto (Dr Freedman), and the Psychology Service, Boston Veterans Administration Medical Center, and the Department of Neurology and Division of Psychiatry, Boston University School of Medicine (Dr Oscar-Berman).

Arch Neurol. 1987;44(4):394-398. doi:10.1001/archneur.1987.00520160036011

• Neuropsychological mechanisms of dementia in Alzheimer's and Parkinson's diseases were compared using a tactile discrimination learning paradigm adopted from animal models. There were two components to the task: (1) tactile original learning (TOL), which is sensitive to parietal lobe damage in nonhuman primates; and (2) tactile reversal of original learning (TRL), a measure of perseveration. The patients with Alzheimer's disease were significantly impaired on TOL compared with demented patients with Parkinson's disease, even though both groups were equated for severity of dementia. On TRL, the patients with Alzheimer's disease and demented patients with Parkinson's disease were both significantly impaired, but the patients with Alzheimer's disease showed significantly more perseverative errors. The mechanisms underlying TOL and TRL deficits may serve to differentiate Alzheimer's from Parkinson's dementia, and may involve selective parietal system lesions.

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